Unfolding the structural insights, magnetic features and magnetocaloric performance of Gd₂FeCrO₆ nanoparticles

Gd₂FeCrO₆ (GFCO) nanoparticles were prepared to investigate their structural, optical, morphological, magnetic, and magnetocaloric features. Room-temperature X-ray diffraction analysis with Rietveld refinement confirms the formation of a single-phase orthorhombic structure (space group: Pbnm). FTIR spectroscopic analysis of GFCO nanoparticles reveals characteristic vibrational bands corresponding to Fe-O and Cr-O stretching and bending modes with local structural distortion. GFCO nanoparticles show multiple absorption bands associated with electronic transitions and the estimated optical band gap of 2.2 eV that is greater than its bulk form. FESEM and TEM analyses confirm agglomerated spherical nanoparticles with an average particle size less than 50 nm. Magnetic measurement shows a broad magnetic anomaly observed around 30 K, which is attributed to the development of short-range Fe³⁺-Cr³⁺ antiferromagnetic correlations preceding the establishment of long-range antiferromagnetic order at T_N ≈ 7 K, which originates from exchange interactions within the Cr³⁺-O-Fe³⁺ network. The observed value of T_N for nanoparticles is higher than that of the bulk counterpart of GFCO. The isothermal magnetisation curves depict an uncompensated spin structure. A maximum value of magnetic entropy (-ΔS = 46.3 J kg^-1 K^-1) is observed at an applied field of H = 90 kOe. The obtained value is significantly higher than that of bulk GFCO. The magnetocaloric effect reveals that GFCO nanoparticles exhibit a first-order like magnetic phase transition.